pysequoia 0.1.15

Provides OpenPGP facilities using Sequoia-PGP library

PySequoia

Provides OpenPGP facilities in Python through Sequoia PGP library. If you need to work with encryption and digital signatures using IETF standard this package is for you!

Note: This is a work in progress. The API is not stable!

Building

set -euxo pipefail
python3 -m venv .env
source .env/bin/activate
pip install maturin
maturin develop

Installing

PySequoia can be installed through pip:

pip install pysequoia

Testing

This entire document is used for end-to-end, integration tests that exercise package's API surface.

Tests assume these keys and cards exist:

# generate a key with password
gpg --batch --pinentry-mode loopback --passphrase hunter22 --quick-gen-key [e-mail]
gpg --batch --pinentry-mode loopback --passphrase hunter22 --export-secret-key [e-mail] > passwd.pgp

# generate a key without password
gpg --batch --pinentry-mode loopback --passphrase '' --quick-gen-key [e-mail] future-default
gpg --batch --pinentry-mode loopback --passphrase '' --export-secret-key [e-mail] > no-passwd.pgp

# initialize dummy OpenPGP Card
sh /start.sh
echo 12345678 > pin
/root/.cargo/bin/opgpcard admin --card 0000:00000000 --admin-pin pin import no-passwd.pgp

Available functions

All examples assume these basic classes have been imported:

from pysequoia import Cert

encrypt

Signs and encrypts a string to one or more recipients:

from pysequoia import encrypt

s = Cert.from_file("passwd.pgp")
r = Cert.from_bytes(open("wiktor.asc", "rb").read())
encrypted = encrypt(signer = s.signer("hunter22"), recipients = [r], content = "content to encrypt")
print(f"Encrypted data: {encrypted}")

decrypt

Decrypts data:

from pysequoia import decrypt

sender = Cert.from_file("no-passwd.pgp")
receiver = Cert.from_file("passwd.pgp")

content = "Red Green Blue"

encrypted = encrypt(signer = sender.signer(), recipients = [receiver], content = content)

print(f"Encrypted data: {encrypted}")

decrypted = decrypt(decryptor = receiver.decryptor("hunter22"), data = encrypted)

assert content == decrypted.content;

sign

Signs the data and returns armored output:

from pysequoia import sign

s = Cert.from_file("signing-key.asc")
signed = sign(s.signer(), "data to be signed")
print(f"Signed data: {signed}")

Certificates API

The Cert class represents one OpenPGP certificate (commonly called a "public key").

This package additionally verifies the certificate using Sequoia PGP's StandardPolicy. This means that certificates using weak cryptography can fail to load or present different view than the one in other OpenPGP software (e.g. if the User ID uses SHA-1 in back-signatures it may be missing from the list returned by this package).

generate

Creates new general purpose key with given User ID:

alice = Cert.generate("Alice <[e-mail]>")
fpr = alice.fingerprint
print(f"Generated cert with fingerprint {fpr}:\n{alice}")

Newly generated certificates are usable in both encryption and signing contexts:

alice = Cert.generate("Alice <[e-mail]>")
bob = Cert.generate("Bob <[e-mail]>")

encrypted = encrypt(signer = alice.signer(), recipients = [bob], content = "content to encrypt")
print(f"Encrypted data: {encrypted}")

merge

Merges data from old certificate with new packets:

old = Cert.from_file("wiktor.asc")
new = Cert.from_file("wiktor-fresh.asc")
merged = old.merge(new)
print(f"Merged, updated cert: {merged}")

User IDs

cert = Cert.from_file("wiktor.asc")
user_id = cert.user_ids[0]
assert str(user_id).startswith("Wiktor Kwapisiewicz")

Notations

Notations are small pieces of data that can be attached to signatures (and, indirectly, to User IDs).

The following example reads and displays Keyoxide proof URI:

cert = Cert.from_file("wiktor.asc")
user_id = cert.user_ids[0]
notation = user_id.notations[0]

assert notation.key == "[e-mail]";
assert notation.value == "dns:metacode.biz?type=TXT";

Notations can also be added:

from pysequoia import Notation

cert = Cert.from_file("signing-key.asc")

# No notations initially
assert len(cert.user_ids[0].notations) == 0;

cert = cert.set_notations(cert.signer(), [Notation("[e-mail]", "dns:metacode.biz")])

# Has one notation now
print(str(cert.user_ids[0].notations))
assert len(cert.user_ids[0].notations) == 1;

# Check the notation data
notation = cert.user_ids[0].notations[0]

assert notation.key == "[e-mail]";
assert notation.value == "dns:metacode.biz";

Certificate management

WKD

Fetching certificates via Web Key Directory:

from pysequoia import WKD
import asyncio

async def fetch_and_display():
    cert = await WKD.search(email = "[e-mail]")
    print(f"Cert found via WKD: {cert}")
    assert cert.fingerprint == "5b7abe660d5c62a607fe2448716b17764e3fcaca"

asyncio.run(fetch_and_display())

Key server

Fetching certificates via HKPS protocol:

from pysequoia import KeyServer
import asyncio

async def fetch_and_display():
    ks = KeyServer("hkps://keys.openpgp.org")
    cert = await ks.get("653909a2f0e37c106f5faf546c8857e0d8e8f074")
    print(f"Cert found via HKPS: {cert}")
    assert cert.fingerprint == "653909a2f0e37c106f5faf546c8857e0d8e8f074"

asyncio.run(fetch_and_display())

CertD integration

The library exposes OpenPGP Certificate Directory integration which allows storing and retrieving OpenPGP certificates in a persistent way directly in the file system.

Note that this will not allow you to read GnuPG-specific key directories. Cert-D does not allow certificate removal.

from pysequoia import Store

cert = Cert.from_file("wiktor.asc")
s = Store("/tmp/store")
s.put(cert)
assert s.get(cert.fingerprint) != None

The certificate is now stored in the given directory and can be retrieved later by its fingerprint:

s = Store("/tmp/store")
assert s.get("653909a2f0e37c106f5faf546c8857e0d8e8f074") != None

OpenPGP Cards

There's an experimental feature allowing communication with OpenPGP Cards (like Yubikey or Nitrokey).

from pysequoia import Card

# enumerate all cards
all = Card.all()

# open card by card ident
card = Card.open("0000:00000000")

print(f"Card ident: {card.ident}")
print(f"Cardholder: {card.cardholder}")

Cards can be used for signing data:

signer = card.signer("123456")

signed = sign(signer, "data to be signed")
print(f"Signed data: {signed}")

As well as for decryption:

decryptor = card.decryptor("123456")

sender = Cert.from_file("passwd.pgp")
receiver = Cert.from_file("no-passwd.pgp")

content = "Red Green Blue"

encrypted = encrypt(signer = sender.signer("hunter22"), recipients = [receiver], content = content)

print(f"Encrypted data: {encrypted}")

decrypted = decrypt(decryptor = decryptor, data = encrypted)

assert content == decrypted.content;

Note that while this package allows using cards for signing and decryption the provisioning process is not supported. OpenPGP card tools can be used to initialize the card.

License

This project is licensed under Apache License, Version 2.0.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the package by you shall be under the terms and conditions of this license, without any additional terms or conditions.

Sponsors

My work is being supported by these generous organizations (alphabetical order):

• nlnet.nl
• pep.foundation
• sovereigntechfund.de